Binaries

The binDesc array points to an array of BinDesc structures. Each structure describes an absolute executable binary involved in the system deployment procedure, such as a bootconf, bootstrap, microkernel, or a driver. These binaries are part of the system image.

typedef struct BinDesc {     
                char*        name;      /* binary symbolic name */     
                int          firstSeg;  /* first segment index */     
                int          lastSeg;   /* last segment index */     
                KnPc         entry;     /* binary entry point */     
                BinType      type;      /* binary type */     
                BinMode      mode;      /* binary loading mode */     
                void*        actor;     /* private for the u-kernel */ 
} BinDesc;

Each binary is composed of a set of segments. The firstSeg and lastSeg fields specify the range of segments within the array of segment descriptors, pointed to by segDesc, that store the binary described by BinDesc.

The type field specifies the binary's type and is set to one of the binType values listed in Table 7-2.

Table 7-2 binType Values

BinType Value	Type of Binary
BIN_BOOTCONF	bootconf program
BIN_BOOTSTRAP	bootstrap program
BIN_REBOOT	reboot program
BIN_DBG_AGENT	system debug agent
BIN_DBG_DRIVER	debug agent communication driver
BIN_KERNEL	microkernel
BIN_DRIVER	a ChorusOS device driver
BIN_SUPERVISOR	a supervisor actor
BIN_USER	a user actor

BinType values are defined in such a way that:

• The BIN_STANDALONE bit is 1 in, and only in, BIN_BOOTSTRAP, BIN_DBG_AGENT, and BIN_DBG_DRIVER.

• The BIN_ACTOR bit is 1 in, and only in, BIN_DRIVER, BIN_SUPERVISOR, and BIN_USER.

• The BIN_KERNEL bit is 1 in, and only in, BIN_KERNEL.

The mode specifies the binary activation mode and can be any combination of the BinMode flags listed in Table 7-3.

Table 7-3 BinMode Flags

BinMode Flag	Meaning
BIN_DEBUGGED	The binary must be launched in debug mode.
BIN_STOPPED	The binary must be loaded but not started.

These flags only have meaning for BIN_SUPERVISOR and BIN_USER binaries. The value of mode is ignored for all other binary types.

The numBins field specifies the number of elements in the array pointed to by binDesc.

segDesc points to an array of segment descriptors. Each item in the array is a SegDesc data structure and describes a segment of the system image. SegDesc is declared in source_dir/nucleus/sys/common/src/kern/bki/bki.h.

typedef struct SegDesc {     
              VmAddr    kaddr;  /* image address */     
              VmAddr    vaddr;  /* execution address (from link editor) */
              VmSize    ksize;  /* image size */     
              VmSize    vsize;  /* execution size */     
              SegType   type;   /* code or data */     
              SegSpace  space;  /* address space type */ 
} SegDesc;

The descriptor specifies two things:

• The location of the segment's image

• Where the segment must be installed for execution

The segment image is stored in the memory bank containing the segment's binary. When the memory bank is installed at the required address, as specified in the BankDesc structure, the segment image can be found at kaddr. The ksize field specifies the size of the segment image contained in the memory bank.

When executed, the segment must be installed at the address specified by the vaddr field and its size must be equal to vsize. If vsize is greater than ksize, the memory from vaddr+ksize to vaddr+vsize must be initialized to zero.

The space field indicates whether a segment belongs to the initial address space. It can be set to one of the values listed in Table 7-4.

Table 7-4 SegSpace Values

SegSpace Value	Meaning
SEG_KSP	segment belongs to the initial microkernel address space
SEG_VIRTUAL	segment does not belong to the initial microkernel address space

Only binaries of the BIN_ACTOR type can hold SEG_VIRTUAL segments.

The value of the type field can be any combination of the bits listed in Table 7-5.

Table 7-5 SegType Bit Values

SegType Bit	Meaning
SEG_XIP	Segment must be executed at its place in the memory bank
SEG_EXEC	Segment contains instructions
SEG_READ	Segment contains read-only data
SEG_WRITE	Segment contains write data

If a segment is executable in place (XIP), and belongs to the initial kernel address space (for example, the SEG_XIP bit is set in the type field and the space field is equal to SEG_KSP), the segment's execution address will be the same as the segment's image address and the segment's execution size will be equal the segment's image size. Therefore, when a memory bank is installed at the address specified by its descriptor (BankDesc::vaddr), all XIP KSP segments that belong to the memory bank will have no particular installation procedure and will be ready for execution.

The numSegs field specifies the number of elements in the array pointed to by SegDesc.